1. Field of the Invention
The invention relates to a two piece nut comprising a nut body having a threaded bore and external wrenching surfaces and a sheet metal cap that encloses one end of the nut body and the wrenching surfaces thereof and is welded to the nut body.
2. Description of the Prior Art
Various methods have been utilized to secure a cap to a nut body to improve the aesthetics of the resulting nut as well as to protect the end of a complementary bolt from the environment. However, when the cap encloses the wrenching surfaces of the nut, the attachment mechanism must be sufficiently strong to prevent accidental loosening under the forces exerted during wrenching of the nut.
For example, U.S. Pat. No. 3,364,806 discloses a nut wherein the cap is secured to the nut body by crimping the free end of the cap around the nut body.
Efforts have also been made to secure the cap to the nut body with adhesive. However, the relatively low tensile and shear strength of adhesives as well as difficulty encountered in masking the nut threads from adhesive present significant problems to the technique.
U.S. Pat. No. 4,123,961 teaches a capped nut wherein the cap is welded to the nut body. The problem of heat generated in the welding process is solved by limiting the weld time thereby to limit metallurgical changes to the cap.